Fluidized desulfurization of hydrocarbon oils with sulfur containing catalyst



' H. s. M GRATH ETAL 2,894,903 FLUIDIZED DESULFURIZATION OF HYDROCARBON;

OILS WITH SULFUR CONTAINING CATALYST 3 Sheets-Sheet 1 July 14, 1959 Filed Nov. '1, 1955 FIG. I

RECYCILE 6A5 I At? ,0 5% PURGE V I4 M-AKE-UP HYDROGEN I3 n l5 l8 CAUSTIC BLOW BACK 5| SOLUTION REGENERATED GAS CATALYST/ EACTOR HIGH PRESSURE CAUSTIC SEPARATOR scRuaBzR 64 0 LOW PRESSURE 53 1: 2 CAUSTIC AND 72 HYDROGEN SULPHIDE 36 69 LOW PRESSURE 24 SEPARATOR 3 Y, 1 34 SP$NT S 73 AA 7 v Y vvv' e, ALY TOTAL LIQUID 30 on.. GAS i I I PREHEATER FIG. 2

0.20 ,3 o o 0.11: Em

o 2.5 7 3.0 3.5 4,0 4.5 SULFUR ON SPENT CATALYST-WT.%

INVENTDRS JOSEPH A. KNAUS HENRY G. MGRATH July 14, 1959 Filed Nov. 7, 1955 NITROGEN IN C FREE LIQUID PRODUCT-W170 SULFUR IN TOTAL LIQUID PRODUC 3 Sheets-Sheet 2 0 was 0 I00 200 300 400 500 eoo 70o INLET HYDROGEN PARTIAL PRESSURE-p'sfa FIG. 4

0.00 0,01 0.02 0.03 0.04 0.05 0.06 0.07 0,09 010 0," 0J2 SEVER ITY FACTOR til-42M 7 A HTORNEYS u y 59 FLUIDIZED bEgIIL X S QQ I S ETAL 2,894,903

N OF HYDROCARBON I OILS WITH SULFUR CONTAINING CATALYST 3 Sheets-Sheet 3 Filed Nov. 7, 1955 FIG. 5

O a z mo O0 650 paid HYDROGEN PARTIAL PRESSURE,

FIG.6

e90 9| o REACTOR TEMPERATURE,:E

INVENTORS JOSEPH A. KNAUS HENRY G MGR'ATH ATTO%EYS United States Application November 7, 1955, Serial No. 545,444 Claims. (Cl. 208-416) Joseph A. Knans, Packto The M. W. Kellogg a corporationof Dela- This invention relates to an improved desulfurization process, and more particularly pertains to a fluid hydrodesulfurization process for hydrocarbon oils.

This application is a continuation-in-part of pending application Serial No. 309,424, filed September 13, 1952, now abandoned.

An object of this invention is to provide an improved desulfurization process which is especially adapted for lf ydrocarbon oils containing high concentrations of sulr.

Another object of this invention is to provide a fluid hydrodesulfurization process for hydrocarbon oils.

Still another object of this invention is to provide a fluid hydrodesulfurization process for hydrocarbon oils whereby substantial removal of combined nitrogen is effected.

A further object of this invention is to provide a fluid hydrodesulfurization process for hydrocarbon oils whereby minimum production of normally gaseous products and/ or carbonaceous material is attained.

Other objects and advantages of the present invention will become apparent from the following description and explanation thereof.

In accordance with the present invention, sulfur containing hydrocarbon oils are desulfurized by the process which comprises contacting said oil 'with a fluidized mass of molybdenum and sulfur containing catalyst in the presence of hydrogen. In a more particular aspect, it is intended operating the present process with a hydrogen partial pressure of at least about 350 p.s.i.a. As another aspect of the invention, it has been found that the removal of combined nitrogen in the hydrocarbon oil is substantially effected by employing a severity factor of at least about 0.025, which severity factor is defined as the result of dividing the catalyst/oil ratio, on a weight basis, by the weight space velocity. Also, it has been found that the production of normally gaseous products can be maintained within an optimum level by operating :at a temperature of not more than about 900 F.; whereas zthe production of coke or carbonaceous material is minimized by using a hydrogen partial pressure of at least :about 375 p.s.i.a. The conditions employed in this process usually result in the net consumption of hydrogen, however, the selection of conditions may be made to obtain a process in which hydrogen is produced in a quantity suflicient to satisfy the requirement for a self- .supporting process.

The hydrocarbon oils to be processed by means of this invention include any hydrocarbon oil containing sulfur, :such as for example, naphtha, kerosene, gas oil, reduced crudes, crude oil, etc. The hydrocarbon oils may be derived from petroleum crudes having an initial boiling point between about 110 and 750 F., and having an end point between about 350 and 1350 F. These hydrocarbon oils may be straight run or virgin stocks, materials which have been previously cracked thermally or catalyti- -cally, or mixtures of straight run and cracked stocks. 'The sulfur content of the hydrocarbon oil will generally atent tion. For example, with obtained. This method has two disadvantages.

be about 0.3 to about 6.0 weight percent with or without combined nitrogen, measured as nitrogen, of about 0.01 to about 1.0 percent by weight. In the case of heavy hydrocarbon oils, for example, those having a gravity of about 10 to about 30 API and boiling in the range of about to about 1200 F., the carbon residue content thereof does not appear to adversely influence the coke yield of our process. This is unexpected in view that it would appear that stocks having high carbon residue contents might produce correspondingly higher coke yields than stocks having lower carbon residue contents. Accordingly, heavy stocks containing about 0.1 to 4.5 percent by weight of carbon residue are satisfactorily processed by means of this invention. Such heavy stocks may contain the sulfur content specified above, or a higher average sulfur content of about 1 to about 5 percent by weight, and yet be successfully desulfurized.

The catalyst employed for this desulfurization process contains, for example, molybdenum oxide and/ or sulfide, with or without a promoter comprising an oxide and/or sulfide of a group VIII metal having an atomic number not greater than 28. The catalytic agent, viz., the oxide and/ or sulfide of molybdenum, is used alone or it is supported on a carrier material. The carrier material can be alumina, silica-alumina, silica-magnesia, silica, pumice, kieselguhr, fullers earth, bentonite clays, Superfiltrol, magnesia, etc. The catalytic agent can comprise from about 0.1 to 25 percent by weight of the total catalyst, preferably about 6 to 15 percent by weight thereof. The catalytic agent can be, for example, molybdenum trioxide, molybdenum trisulfide, etc. The promoter includes, for example, cobalt oxide and/or sulfide, iron oxide and/or sulfide, and nickel oxide and/0r sulfide. When employed, the promoter comprises about 1 to 10 percent, preferably about 1 to 5 percent, based on the total weight of catalyst. In order to enhance the stability of the catalyst at elevated temperatures, silica can be used in an amount of about 0.5 to about 12 percent by weight, based on the total catalyst.

The condition of the catalyst during the desulfurization reaction, insofar as the sulfur content is concerned, is an important factor. It has been found, for example, that the catalysts hereinbefore mentioned are most effective in promoting desulfurization when they have a certain sulfur content. Sulfur on the catalyst may be present as chemically combined sulfur, it may be physically combined with the catalytic material, or it may be present in both forms. Generally, it is desirable to operate the process with a catalyst having a sulfur concentration of between about 1 and about 7 percent by weight. For optimum performance, however, it is preferred to employ a catalyst having at least 3.2 percent of sulfur and I more usually between about 3.5 and 5 percent.

In the past it has been the practice in conventional fixed bed desulfurization to utilize two general methods to provide catalysts having the required sulfur concentraa catalyst initially free of sulfur, in one method, the catalytic material is contacted with the material to be desulfurized under desulfurization operating conditions and, after an activation period of 4 to about 20 hours during which the feed material is only partially desulfurized, the sulfur content of the catalyst increases to the point where good desulfurization is First, the feed material passed in contact with the catalyst during the activation period is only partially desulfurized and must therefore be treated again after the catalyst becomes activated and second, when the catalyst becomes spent and is regenerated for the removal of carbonaceous material, the sulfur contained on the catalyst is also removed. .The other method of providing an active catalyst concerns treating the catalyst prior to the desulfurization reaction with a sulfur containing material such as, for example hydrogen sulfide, elemental sulfur, etc. This method has the advantage of eliminating the need for a second treatment of partially desulfurized feed material, however, it too has the second disadvantage noted above, namely that regeneration of spent catalyst removes both sulfur and carbonaceous material from the catalyst.

Catalysts suitable for desulfurization, as previously mentioned, may contain as the catalytic element metallic oxides and/or sulfides. Thus it is possible to start with a sulfide catalyst which contains the requisite amount of sulfur and thereby eliminate the activation or sulfiding treatment. However, as in the case of catalysts which are initially free of sulfur, these catalysts also lose their sulfur during regeneration and after once used, are subject to the same disadvantages as the oxide catalysts.

In the method of this invention, the disadvantages of the conventional desulfurizing a process with respect to maintaining sulfur on the catalyst is eliminated by carrying out the process in a system involving the fluid bed technique. For the fluid system contemplated herein, generally the catalytic material is finely divided, having a particle size not greater than 250 microns or more usually in the range of about to about 100 microns. The catalytic material in this finely divided state is fluidized by the upward passage of gasiform materials therethrough. The passage of these materials through the mass of finely divided catalyst is measured in terms of the superficial linear gas velocity, which is generally in the range of about 0.1 to about 50 feet per second, more usually about 0.1 to about 6 feet per second. In commercial practice, it is preferred to employ a superficial linear gas velocity of about 1 to about 2 /2 feet per second because a dense fluidized phase is thereby produced, providing excellent contact between the particles and medium.

In carrying out the fluid desulfurization operation, carbon is formed and is deposited on the catalyst. It is desirable, therefore, to provide two processing zones, one for the reaction of the feed material and the other for the regeneration of catalyst to remove carbon. Catalyst spent by the deposition of carbonaceous material is circulated to the regenerator wherein the carbonaceous material is removed by combustion with an oxygencontaining gas before being circulated back to the reaction zone. Under normal conditions of operation it is desirable to maintain a substantially constant quantity of catalyst in the reaction zone, therefore all of the regenerated catalyst is usually returned to this zone. In some cases, however, it may be desirable because of the nature of the catalyst and/or the type of contamination produced in the desulfurization reaction to either discard the used catalyst or to suificiently rework it to provide a substantially new catalyst. An example of this would be where the catalyst is poisoned by metals contained in the feed material to be desulfurized. In a case of this type, it might be desirable to discard an inexpensive catalyst whereas an expensive catalyst would more likely be reworked to remove the contaminants. Where the catalyst is discarded or is withdrawn and sufiiciently reworked to constitute a new catalyst, there is in effect no return of catalyst to the reaction zone and the catalyst inventory therein is maintained entirely by the introduction of fresh catalyst.

In the normal course of operation, catalyst is frequently lost from the system and this loss is made up usually by introducing fresh catalyst to the reaction zone. Inasmuch as catalysts often suffer a permanent loss in activity after repeated regeneration, it may be desirable from time to time to replace a portion of the catalyst inventory with fresh catalyst in order to maintain the average activity of the catalyst at a constant level. More usually, this is accomplished permanently by withdrawing spent catalyst from the system either before or after regeneration and introducing fresh make-up catalyst into the reaction zone. In a system where the spent catalyst is discarded or reworked the average activity of the catalyst in the reaction zone usually is maintained by controlling the rate of withdrawal of spent catalyst.

Although the invention is usually applied in a system wherein it is necessary to withdraw spent or deactivated catalyst from a desulfurization zone either continuously or intermittently, it also includes within its scope the maintenance of catalyst surfur content in other systems. A typical example is where the operation is substantially non-regenerative for the reason that the desulfurization catalyst does not become spent or deactivated. In such a system, in order to maintain the preferred catalyst sulfur concentration, it may be necessary to remove catalyst of high sulfur content and introduce an equal amount of make-up catalyst of low surfur content.

It is contemplated that the total amount of catalyst entering the reaction zone whether fresh, regenerated, reworked, etc., is included in the term catalyst circulation as used hereinafter.

It has been found that under the reaction conditions of temperature, pressure, hydrogen partial pressure, etc., hereinafter specified that the average sulfur content of the catalyst in the reaction zone can be maintained at a desired level or within a desired range by appropriately controlling the catalyst circulation rate. In other words, by controlling the rate of withdrawal of catalyst from the reactor and the amount of catalyst introduced thereto, the quantity of sulfur on the catalyst in the reaction zone can be controlled to provide the desired concentration. Usually, the catalyst introduced to the reaction zone whether fresh, regenerated or reworked will be substantially sulfur free; however, the introduction of make-up catalyst containing small amounts of sulfur is within the scope of the invention. The required catalyst circulation to provide the sulfur concentrations previously specified usually is between about 0.004 and about 3 pounds per hour per pound of feed, and preferably between about 0.02 and about 1 pound per hour per pound of feed. If it is desired to maintain a substantially constant catalyst sulfur content, it is necessary to continuously withdraw catalyst from the reaction zone for regeneration, disposal or reworking. On the other hand, if it is desirable to allow the sulfur concentration to fluctuate between certain values, this may be accomplished by intermittent withdrawal of catalyst.

It is customary in the conventional operation to perform routine process tests on the reaction zone products. Normally such tests will be suflficient to indicate any deviation in catalyst sulfur content from the prescribed value or range. However, it may be desirable particularly when starting up a unit or when processing an unfamiliar feed stock to provide for periodic sampling and analysis of the catalyst present in the reaction zone. If necessary, such a test may be made a part of the daily routine in an operating unit.

The desulfurization process of this invention is conducted at a temperature of at least about 600 F. and can be carried out at temperatures where cracking effects become undesirably excessive. The desulfurization temperature is usually about 650 F. to about 900 F. At

temperatures greater than about 900 F., there is a substantial increase in the production of normally gaseous products, e.g., hydrocarbons having 1 to 3 carbon atoms; consequently, it is desirable to operate below this temperature in order to avoid excessive loss of hydrocarbon material through gas formation, etc.

With respect to nitrogen removal, it is desirable to operate the process at a high temperature in the order of about 800 F. to about 1000 F. because nitrogen removal is favored at higher temperatures. However, when nitrogen removal is effected simultaneously with sulfur removal, it is preferred to employ a temperature of about 800 F. to about 900 F. If greater emphasis is to be placed on obtaining high yields of desulfurized product, then it is preferred to employ temperamres which are lower than the optimum temperatures for nitrogen removal. The removal of nitrogen is important, because if the desulfurized product is to serve as a charge material for a catalytic operation, it is important to remove as much of the combined nitrogen as is possible in order to avoid the deactivating effects caused by the combined nitrogen on the surface of the catalytic material. In a manner not too clearly understood, nitrogen appears to become fixed on the surface of the catalyst, particularly in the case of an acid type of catalyst, and renders the catalyst less active for the particular reaction or process contemplated. Hence, in the practice of this invention, it is desirable to fix the conditions so as to be able to operate Within the range for obtaining optimum removal of nitrogen as well as optimum or minimum production of product or fixed gases. At the temperature specified above, the process is usually operated at a total pressure of about 500 to about 1200 p.s.i.g. With respect to nitrogen removal, it is preferred to operate at higher pressures, such as, for example in the range of about 800 to about 1200 p.s.i.g. At the higher pressures, more effective removal of nitrogen is attained. The total pressure of the process becomes important insofar as it makes possible procuring desired hydrogen partial pressures. Generally, for this process, the hydrogen partial pressure, measured at inlet conditions, is in the range of about 200 to about 1000 p.s.i.a.

For optimum performance, depending upon the result desired, the hydrogen partial pressure is of considerable importance. For example, when the primary aim is to obtain a desulfurized product of unusually low sulfur content, for optimum performance it is desired to operate the process at a hydrogen partial pressure of at least about 350 p.s.i.a. As will be shown later, the effectiveness of sulfur removal does not increase markedly when the hydrogen partial pressure is raised above the optimum pressure of about 350 p.s.i.a. The hydrogen partial pressure is also important in determining the carbon yield of the process. In the type of process contemplated in the present invention, it is desirable to produce as little carbon or coke and normally gaseous hydrocarbons as. is possible, because they represent an economic loss in view of the limited use of these materials. In the case of carbon, the material possesses no economic value, and further, it causes a temporary deactivation of catalyst thus necessitating another step in the reaction whereby carbon removal is effected by combustion. For optimum performance of the process, it is desirable with respect to carbon yields to employ a hydrogen partial pressure of at least about 375 p.s.i.a. At values greater than 375 p.s.i.a., the decrease in carbon yield is not significant, therefore, the process can be satisfactorily operated using hydrogen partial pressures of lower values in the optimum range.

The severity of the-desulfurization process is measured in terms of a severity factor, which is obtained by dividing the catalyst to oilratio by the weight space velocity. The catalyst to oil ratio is determined on the weight. basis, and in the case of a'fluid system, it measures the relative rates of catalyst and oil being charged to the reaction zone, based on inlet conditions. The weight space velocity in the severity factor is determined on a weight basis, and it is measured as thepounds of oil. charged to the reaction zone at an hourly basis per pound of catalyst which is present therein. Generally, the catalyst to oil ratio will be in the range of about 0.004 to about 3, and preferably about 0.02 to about 1. In general, the weight space velocity is in the range of about 0.25 to about 10, preferably about 0.5 to about 5. Thesetwo conditions, viz., the catalyst to oil ratio and the weight space velocity are employed to determine the severity ofthe desulfurization operation. Generally, the severity factor is in the range of about 0.001 to about 0.3. However, with respect to nitrogen removal, this 6 severity factor is preferably at least about 0.025 and up to about 0.3 or higher. It is noted from experimentation, that the rate of removal of nitrogen in operations involving severity factors below the optimum value specified above is subject to rapid changes; whereas for optimum nitrogen removal, severity factors of at least about 0.025 are highly desirable.

In the operation of the process, the conditions can be varied so as to obtain either a net consumption of hydrogen 01 a net production of hydrogen. Hydrogen production or consumption is determined by a proper selection of operating conditions, hence, the description of the conditions hereinabove will apply for both types of operations depending upon a suitable choice thereof. Normally, more effective removal of sulfur and nitrogen occurs under conditions of net consumption of hydrogen, because less feed material is used in furnishing the hydrogen which is involved in the operation producing hydrogen. Furthermore, an operation involving a net consumption of hydrogen results in higher yields of desulfurized product and greater nitrogen and sulfur removal under comparable operating conditions.

In the present invention, it is desirable to operate the process under such conditions that the amount of hydrogen produced is sufiicient to sustain the process without the need for extraneous hydrogen. This can be effected by employing preferred conditions, such as for example, a temperature in the order of about 700 F. to about 850 F a total pressure in the range of about 50 to about 250 p.s.i.g., a weight space velocity of about 0.1 to about 5, a catalyst to oil ratio of about 0.1 to about 10 and a hydrogen rate of about 500 to about 5000 standard cubic feet (measured at 60 F. and 760 mm.) per barrel of oil feed (1 barrel equals 42 gallons). In this type of a process, the catalyst would be one which combines the dehydrogenization of the naphthene compounds contained in the hydrocarbon oil with the hydrogenization of the organically combined sulfur to form hydrogen sulfide. The hydrogen produced in the process may serve as the sole supply of hydrogen to the reaction zone under steady state conditions. In the start-up operation, hydrogen can be added to the system or the system can be allowed to function until the hydrogen produced is sufficient to satisfy the requirements. This type of a system in contrast to one in which hydrogen is consumed is not as effective in the removal of sulfur and nitrogen, nor does it yield desulfurized product in quantities obtained in an operation involving the net consumption of hydrogen. Another .important advantage in using this process under conditions of net consumption of hydrogen is the low yields of coke or carbon which are obtained. This represents an economic advantage and also makes possible the employment of longer reaction periods because the catalytic activity is maintained for longer periods of time. When practicing the invention, to obtain a net consumption of hydrogen, it is preferred to employ a hydrogen rate of about 500 to about 12,000 s.c.f.b.

The amount of carbonaceous material on the catalyst .in the desulfurization zone is generally in the range of about 0.5 to about 20 percent by weight based on the total catalyst. It is preferred, however, to maintain the carbonaceous material on the catalyst in amounts of about 1 to about 10 percent by weight in order to avoid diminution of desulfurization efficiency as Well as decrease in nitrogen removal. The carbonaceous material on the catalyst is controlled by a regeneration treatment which involves contacting the catalyst with an oxygen containing gas, e.g., air; oxygen; diluted air, containing about 1 to about 10 percent by volume of oxygen; etc., under suitable conditions to burn said carbonaceous material. The temperature of regeneration is about 600 F. to about 1200 F., preferably about 950 F. to about 1150 F. The pressure of regeneration can be at the same level which was mentioned hereinabove with respect to the reaction zone, or it can be operated at a higher or' lower level in the range specified. Usually the regenerated catalyst will contain carbonaceous material in an amount of about to about 1 I percent by weight.

In order to provide a better understanding of the present invention, reference will be had to the accompanying drawings which form a part of this specification.

Figure 1 is a schematic diagram of a system used to evaluate this invention;

Figure 2 is a correlation showing the effect of sulfur I content of the catalyst on sulfur removal;

ature on dry gas yield.

In Figure 1, the reactor 10 is a vertical, cylindrical vessel comprised of a 3 inch Schedule 40 stainless steel pipe 44 feet long. Superimposed on the reactor proper It is an enlarged cylindrical section employed as a filter housing 11 made from an 8 inch Schedule 80 stainless steel pipe. The filter housing contains three stainless steel bayonet filters (not shown) which serve to separate entrained finely divided solids from the effiuent gases. The effluent gases pass through three overhead lines 13, each one containing two way acting valves 14, to which three lines 15 containing blow-back gas are connected for supplying the blow-back gas from a main heater 16. The filters are automatically blown back alternately at periodic intervals through a master time cycle control mechanism not shown. Regenerated catalyst is introduced into the top part of the reactor proper 10 through line 18. Catalyst is withdrawn from the reactor 10 through a line 20, which is located about feet from the bottom thereof. The catalyst is then charged into a lock hopper system shown schematically as 22, and it is discharged therefrom through a line 24.

Oil feed is charged from a source 30 and by means of a pump 31, it is pumped to an oil-gas preheater 33 via a line 34. Hydrogen-containing gas or recycle gas is mixed with the oil feed in line 34 by charging same through a line 36 which is connected to same. In preheater 33 the oil and gas are heated to the desired temperature and then fed into the botom end of the reactor through a line 37. After the oil and hydrogen are in contact with the catalyst for the desired length of time, the reaction product thus produced is discharged from the reaction system by means of lines 13, and these lines join with a single line 39 for the passage of product as a single stream therethrough. The product stream is then passed through a condenser 40 wherein a substantial part of the normally liquid materials is condensed, and the total stream passes to a high pressure separator 43 by means of a line 44. In the separator 43, the normally gaseous materials are removed from the product bulk overhead through a line 46, and thence it passes into the bottom part of a caustic scrubber 47 for the removal of hydrogen sulfide therefrom. A 20 percent by weight caustic solution (NaOH in water) is fed into the toppart of the scrubber by means of supply line 49, pump 50 and entrance line 51. The caustic solution and product gas flow countercurrently to each other, thus the spent caustic is discharged from the bottom end of the scrubber through a line 53 and the product gas substantially free of hydrogen sulfide is discharged from the system via an overhead line 55. The scrubbed product gas contains hydrogen which can be recycled to the reactor, hence, after passing through the control valve 57 in line 55, it can be partly purged through a vent 58 to prevent buildup of gases other than hydrogen in the system, and the remainder is passed through line 60 to a compressor 61. Make-up hydrogen is fed into line 60 via line 63 in order to raise the hydrogen concentration. The com- Gravity, API

8 pressed hydrogen-containing stream is-then recycled to line 34 of the preheater through line 36, in which there is installed a control valve 64 for rate control.

The separated liquid in separator 43 is discharged from the bottom thereof by means of a line 68 in which there is located a control valve 69 for maintaining the pressure within the system. The discharged liquid is then fed into a second separator 70 which is operated at a low pressure, e.g., atmospheric pressure. Any material which is normally gaseous at this pressure is separated from the liquid and removed overhead from the separator through a line 72. The desulfurized liquid product is withdrawn from the separator 70 through a line 73 which is connected to the bottom thereof.

In operation, the temperature of the desulfurization reaction was indicated by thermocouples (not shown) located at spaced points along the length of the reactor. Ten thermocouples were employed for this purpose. Catalyst was withdrawn from the reactor intermittently, i.e., at periodic intervals spaced usually about 8 hours apart. The catalyst was regenerated in a separate vessel not shown and then introduced into the reactor in the same intermittent manner described above for the spent catalyst.

Employing the test unit shown in Figure 1, various sulfur containing stocks were desulfurized in accordance with this invention. These stocks are given in Table I below.

Table I Feed Stock Designation ASTM Distillation, F.

IBP

E.P Sulfur (total oil), Wt. Percent Sulfur (06.011 washed), Wt. Percent. Nitrogen, Wt. Percent Aniline Pt., F Kattwinkel Absorption, Vo Percent Olefins, Mol Percent Carbon Residue, Wt. Percent ASTM Four (main), F

l point. 2 Distillation at 760 mm. to 30% overhead, then remainder of distillation at 10 mm.

3 95% by volume overhead of Stock D.

The catalysts used in these experiments are given in Table II below.

Table II Catalyst Designation I II III Chemical Analysis:

Ignition Loss, Wt. Percent 4.0 0.5 1. 4 S102, Wt. Percent 3. 3 2. 7 3. 6 M O 8. 5 9. 6 8.9 3. 2 3.0

0.6 8. 4 8.1 2. 1 3. 8 4. 0 12. 2 19. 8 7. 6 45.3 38. 6 9.0 39. 8 29. 4 71. 4 Recovery 105.0 100.1 Air Rate, Liters/min 13.0 13.0 13.0 Screen Analysis:

Larger than 40 mesh, Wt. Percent 0.0 0. 0 0.9 40-100 O. 0 14. l 54. 8 100140 16. 5 10.2 11.4 -200 50.2 20.4 11.4 200325 18. 6 32. 5 8. 7 Pan 14. 7 22.8 12. 8 Settled Deusity1b./cu. ft 53 57 1 By difference.

A series of experiments was made to determine the effect of catalyst sulfur content on the extent of desulfurization. These runs are reported in Table III.

iqui

From Figure 3, it is to be noted that This correlation is shown in Figure 3 of the In order to more clearly demonstrate the eflFect of Another series of experiments was made to show the Table III The in Table VII abovewere. correlated to show the eflfect of hydrogen partial pressure on carbon yield, and this is found in Figure Figure 5 demonstrates that the optimum carbon yield is obtained at hydrogen partial pressures of at least about 375 p.s.i.a. Furthermore, by comparing run 3 with run 4 and run 2. with run 5, it is noted that those runs involving a'feed containing a carbon residue of 0.69 percent by weight did not result in higher carbon yields than those runs using a feed of 0.19 percent-by weight carbon residue. This is an important aspect of this process, because it demonstrates that highly asphaltic stocks can be processed under the optimum hydrogen partial pressure, i.e., at least 375 p.s.i.a., without incurring abnormally high carbon yields.

Another series of experiments was made to show the effect of temperature on dry gas product, i.e., product including hydrocarbons of one to three carbon atoms. These results are shown in Table VIII below.

alumina catalyst for desulfurizing gas oil. Run 2 was made with the same catalyst for desulfurization of a blend of kerosene and naphtha. The last run, No. 3, was made on a virgin gas oil. These runs serve to show the versatility of this process, however, this invention is unusually effective for high asphaltic and sulfur containing high boiling or heavy residual stocks.

Having thus provided a description of this invention by furnishing specific examples, no undue limitations or restrictions should be imposed by reason thereof, but that the scope of this invention is defined by the appended claims.

We claim:

1. A hydrodesulfurization process for sulfur containing hydrocarbon oil which comprises contacting said oil with a fluidized finely divided mass of molybdenum oxidesulfur containing catalyst in a conversion zone in the presence of hydrogen under suitable conditions to desulfurize said oil, removing catalyst from the conversion Table VIII Run No 1 2 3 4 5 Fee D D D E E Catalyst II II II III II 7 Length of Run, hrs 16 16 20 18. 40. Operating Conditions:

Temperature, F 920 900 870 850 850 Pressure, p.s.i.g 800 300 800 500. 500 Space Vel., Wo/hr./W.... 0. 52 0. 46 0. 51 0. 53 0. 58 Circulating Gas Rate, s.c.f. 7, 590 8, 180 8, 080 8, 520 7, 710 M01 Percent; H; in Gas 83.8 85. 6 .4 85. 3 86. 4 Catalyst Residence Time, hrs- 57 62 33 14 44 Average'Carbon on Catalyst, W 8. 3 9. 3 7. 8 7. 5 6.8 Average Sulfur on Catalyst, Wt. Percent 3.6 3. 6 2. 6 2. 5 3.4 Inlet Partial Pressures, p.s.i.a.:

1 Dry ga5-C1Ca, inclusive.

The results reported in Table VIII above were correlated to give Figure 6. It is to be noted from Figure 6 that a temperature greater than about 900 F. results in a very rapid increase in production of dry gas. Hence, for optimum performance, the temperature should be maintained not higher than about 900 F., otherwise, dry gas production becomes excessive.

A series of experiments was made on different feed stocks and catalyst. These runs are given in Table IX below:

Table IX Run No 1 2 3 Feed A C B Catal I I III Length of Run, hrs" 47 24 22 Operating Con drtlons Temperature, 1* 805 665 850 Pressure, p.s.i.g 500 785 500 Space Vel., W0/hr./Wc 0. 94 0. 49 2. 9 Circulating Gas Rate, s.c.f.b 5, 240 5, 760 7, 930 M01 Percent H in Gas 82. 8 98.8 84. 5 Catalyst Residence Time, Hrs 39 37 47 Average Carbon on Catalyst, Wt. Percent- 2. 9 1. 8 13. 7 Average Sulfur on Catalyst, Wt. Percent.-- 1. 5 1. 6 3. 8 Inlet Partial Pressures, p.s.i.a.:

Oil eed 38 105 33 Hydrogen 395 690 405 Product Yields0utput Bas Dry Gas, Wt. Percent- 1. 3 0.3 2.1 Carbon, Wt. Percent.-- 0.08 O. 13 0.06 Total Butanes, Vol. Percent. 0.7 0.5 0.7 Liquid Recovery (0 inc.), Vol. Percent. 100. 2 101.8 100.1 Hydrogen Consumed, s.c.f.b 386 374 Hydrogen Sulfide Produced, s.c.f.b 16 26 91 Product Inspections:

Debutanized Liquid Product- Gravlty, API 34. 2 52. 5 37. 7 ASTM Dist 10 394 187 50.- 590 283 90 409 Vol. Percent 400 Sulfur (Total Oil), Wt. Perce Sulfur, Wt. Percent (CdClz or N OH washed) 0. 12 0. 03

In Table IX, run 1 illustrates the use of molybdenazone, introducing into said conversion zone catalyst having a lower sulfur concentration than the catalyst removed from the conversion zone and controlling the catalyst circulation rate to maintain a catalyst sulfur content between about 1 and about 7 percent by weight.

2. A hydrodesulfurization process for sulfur containing hydrocarbon oil which comprises contacting said oil with a fluidized finely divided mass of molybdenum oxidesulfur containing catalyst promoted with an oxide of a group VIII metal having an atomic number not greater than 28 in a conversion zone in the presence of hydrogen under suitable conditions to desulfurize said oil, removing catalyst from the conversion zone, introducing into said conversion zone catalyst having a lower sulfur concentration than the catalyst removed from the conversion zone and controlling the catalyst circulation rate to maintain a catalyst sulfur content between about 1 and about 7 percent by weight.

3. The process of claim 2 wherein the sulfur containing catalyst is promoted with a cobalt oxide.

4. A hydrodesulfurization process for sulfur containing hydrocarbon oil which comprises contacting said oil with a fluidized finely divided mass of molybdenum oxidesulfur containing catalyst in a conversion zone at a hydrogen partial pressure of at least about 350 p.s.i.a., and a severity factor of about 0.025, removing catalyst from the conversion zone, introducing into said conversion zone catalyst having a lower sulfur concentration than the catalyst removed from the conversion zone and controlling the catalyst circulation rate to maintain a catalyst sulfur content between about 1 and about 7 percent by weight.

5. A hydrodesulfurization process for sulfur containing hydrocarbon oil which comprises contacting said oil with a fluidized finely divided mass of molybdenum oxidesulfur containing catalyst in a conversion zone in the presence of hydrogen under suitable conditions to desulfurize said oil, said catalyst becoming deactivated during this process, removing deactivated catalyst from the conversion zone, introducing into said conversion zone catalyst having a lower sulfur concentration than the catalyst removed from the conversion zone and controlling the catalyst circulation rate to maintain a catalyst sulfur content between about 1 and about 7 percent by Weight.

6. A hydrodesulfurization process for sulfur containing hydrocarbon oil which comprises contacting said oil with a fluidized finely divided mass of molybdenum oxidesulfur containing catalyst in a conversion zone at a hydrogen partial pressure of at least about 350 p.s.ia, at a temperature not exceeding 900 F. and a severity factor of at least about 0.025, said catalyst becoming deactivated during this process, removing deactivated catalyst from the conversion zone, introducing into said conversion zone catalyst having a lower sulfur concentration than the catalyst removed from the conversion Zone and controlling the catalyst circulation rate to maintain a catalyst sulfur content between about 1 and about 7 percent by weight.

7. The process of claim 6 wherein the sulfur containing catalyst is promoted with cobalt oxide.

8. A hydrodesulfurization process for sulfur containing hydrocarbon oil which comprises contacting said oil with a fluidized finely divided mass of molybdenum oxide-sulfur containing catalyst in a conversion zone at a hydrogen partial pressure of at least about 350 p.s.i.a. and a severity factor of about 0.025, said catalyst becoming deactivated during this process by the deposition of carbonaceous material thereon, passing the deactivated catalyst to a regeneration zone wherein deposited carbonaceous material and sulfur are removed by burning with oxygen, introducing into said conversion zone a quantity of regenerated catalyst equal to that removed and controlling the catalyst circulation rate to maintain a catalyst sulfur content between about 1 and about 7 percent by weight.

l6 9. A hydrodesulfurization process for sulfur containing hydrocarbon oil which comprises contacting said oil with a fluidized finely divided mass of molybdenum oxide-sulfur containing catalyst in a conversion zone at a hydrogen partial pressure of at least about 350 p.s.i.a., at a temperature not exceeding about 900 F. and a severity factor of at least about 0.025, said catalyst be 'oil with a fluidized finely divided mass of molybdenum oxide-sulfur containing catalyst in a conversion zone in the presence of hydrogen under suitable conditions to desulfurize said oil, said catalyst becoming deactivated during this process by the deposition of carbonaceous material thereon, passing the deactivated catalyst to a regeneration zone wherein deposited carbonaceous material and sulfur are removed by burning with oxygen, returning the regenerated catalyst to the conversion zone and controlling the catalyst circulation rate to maintain a cat- 'alyst sulfur content of between about 1 and about 7 percent by weight.

Refereuces Cited in the file of this patent UNITED STATES PATENTS Cole Apr. 6, 1946 Joyce Jan. 18, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION July 14, 1959 Patent No. 2 ,894 ,903

Henry G, McGrath et al,

in the printed specification ppears that the said Letters It is hereby certified that error a of the above numbered patent requiring correction and Patent should read as corrected below.

d hydrogenation line 37, for "hydrogenization rea th column thereof, under the heading 13",

column 14, lines 40 and 41, claim 1,

67, claim 4, column 15, lines 4 and line 35, claim 8, column 16, line ike out "controlling the catalyst and insert instead line 55, claim 2, line 69,

Column 6, column 8, line 43, Table I, fif

last line, for "=5" read +5 lines 66 and lines 53 and 54, claim 2,

5, claim 5, lines 17 and 18, claim 6,

11,, claim 9 and line 28, claim 10, str

each occurrence,

circulation. rate to maintain", we maintaining column 14, line 42, claim 1,

line 20, claim 6, line 3'7, claim 8,

claim 4, column 15, line 6, claim 5,

column 16, line 1.6, claim 9, and line 30, claim 10, after Weight and before the period, each occurrence, insert by controlling the rate of withdrawal of catalyst from said conversion zone and the rate of in of low sulfur content catalyst to said conversion zone Signed and sealed this lst day of December 1959.,

(SEAL) .Attest:

KARL Iia AXLINE Attesting Officer ROBERT Go WATSON troduction Commissioner of Paten 

1. A HYDRODESULFURIZATION PROCESS FOR SULFUR CONTAINING HYDROCARBON OIL WHICH COMPRISES CONTACTING SAID OIL WITH A FLUIDIZED FINELY DIVIDED MASS OF MOLYBDENUM OXIDESULFUR CONTAINING CATALYST IN A CONVERSION ZONE INB THE PRESENCE OF HYDROGEN UNDER SUITABLE CONDITIONS TO DESULFURIZE SAID OIL, REMOVING CATALYST FROM THE CONVERSION ZONE, INTRODUCING INTO SAID CONVERSION ZONE CATALYST HAV- 